In order to provide increased rideability and stability for a snowmobile, strut-type suspension assemblies for the steering ski or skis are meeting with increased favor, and are supplanting the older leaf-spring type suspensions. A strut-type suspension assembly includes a stationary member which is fixed to the chassis of a snowmobile, and a movable tube which is slidable relative to the stationary tube. A steering ski is connected pivotally to the lower end of the movable tube by means of a pivot pin which is arranged transversely with respect to the running direction. The movable tube is biased to return downwardly in order to perform its suspension function. It has been customary practice to mount the pivot pin directly on, and transverse to, the axis of the movable tube.
A strut-type steering ski suspension assembly resists sway and lateral deflection during cornering better than the leaf-spring type of suspension. However, it does have the draw-back that its overall height is greater. This results from the fact that in order to provide sufficient stability and strength, the stationary tube must have a considerable length. Also, the movable tube must be long enough to provide for the cushioning stroke.
As known suspension assemblies become more elongated, they must protrude additionally from the chassis cowling. This cowling is generally rounded for best appearance and performance. The protrusions adversely affect the appearance.
Especially when the snowmobile is equipped with a pair of steering skis, there is the further draw-back that the suspension assembly must protrude considerably from the cowling while still leaving the spacing between skis (i.e. the tread) unchanged, or the tread must be narrowed to such an extent as to sacrifice driving stability. Because the steering ski or skis are attached to the movable tube of a strut by means of a pivot pin which is located just below the movable tube, the total height in conventional installations is enlarged to the extent necessary to accommodate this pivot pin. This accommodation is made either by causing a larger protrusion from the cowling or by shortening the cushioning stroke, both of which are undesirable expedients.
It is an object of this invention to increase the effective cushioning stroke of the suspension assembly without increasing its height, and thereby to minimize or even to eliminate the protrusion of the system from the cowling for the same stroke.
It is another object of the invention to improve the stability of the vehicle, by placing the mounting pin of the ski rearwardly of the strut so it stably follows the strut, somewhat similar to the action of a caster.
Yet another object of the invention is to provide a improved mounting of the ski to the movable tube such that the ski can readily be removed and replaced without removing or replacing the movable tube, and so that the offset of the ski mounting pin can be changed merely by substitution with a modified mounting.